Optical recording elements for storing information are known. Magneto optic and phase change elments and the currently popular compact disk or CD. Optical information is stored in the form of low specular reflectivity marks or pits on an otherwise reflective background.
One recently disclosed compact disk element is the so called "Photo CD". In this element, conventional photographic film is first processed in a conventional manner. Then, the images from the film are digitized and the digital information is recorded in a CD readable form on an optical recording material. Images can then be played back by means of a CD type player on a conventional television.
A typical Photo CD structure contains a substrate that is successively overcoated with an optical recording layer, a metal reflective layer, and one or more protective layers. The protective layers are typically photopolymerizable or UV-curable compositions designed to protect the underlying layers from physical damage and/or loss of recorded information.
Gold and aluminum are commonly used as the metal reflective layer in optical disks. Gold is preferred in some applications because it is more reflective than aluminum. However, gold is also a notoriously difficult surface for achieving adequate polymer/metal adhesion. Current photopolymerizable compositions of which we are aware form protective layers that exhibit poor adhesion to gold. Poor protective layer adhesion to gold significantly decreases the ability of a protective layer to protect the metal reflective layer.